Yes I do mean backing off the jib halyard which does loosen the rig. Sheet jib and main sheets in hard for upwind sailing. You may want to travel out the jib and main a bit too.
This method depowers a 16 beautifully.
Start out with your rig at your normal tension and mark the halyard at the black band. If you find the boat wants to fly a hull too much, loosen the jib halyard until the boat settles down and is quite manageable. You will need to head up into the wind each time you want to make an adjustment and then sail upwind again to test your setting. With the halyard marked you can easily see how much you have backed off the halyard and reset it if the wind drops.